The invention relates to a securing device for axially connecting a sleeve-shaped end section of a first fluid line part to an end section, which is designed as a pointed end, of a second fluid line part. Furthermore, the invention relates to a fluid line connection which has a securing device of this type.
In the context of the invention, the expression “fluid line part” comprises all types of tubular shaped pieces or shaped parts in pipelines, such as, for example, pipes, pipe bends, T pieces, Y pieces, sleeves, U pipes, pipe branches, reducing means or reductions, pipe sockets and the like. Embodiments below which relate to pipes, pipelines and pipe connections should therefore not be understood as being restricted to pipes but rather in general to abovementioned types of fluid line parts and the connections thereof. Similarly, the term “fluid” includes both gases and liquids within the meaning of the invention.
It is generally known to connect end sections of fluid line parts, such as, for example, of pipes, to one another by means of screw, flange, clamping or sleeve connections in order to form a fluid line or pipeline.
In the case of screw connections, the end sections of the pipes or fluid line parts have a thread, as a result of which the end sections of the pipes can be connected securely to one another. However, screw connections of this type to a certain extent restrict the flexibility of laying pipes and, furthermore, require time-consuming installation operations. Screw connections of this type are therefore customarily used only in pipes having small nominal widths, but for nominal pressures of up to several hundred bar.
With greater nominal widths of the pipes or fluid line parts, use can be made of flange connections in order to connect pipe sections tightly, but releasably to one another. For the tightness of the flange connection, the contact pressure of the sealing surfaces against the seal located inbetween is crucial. The contact pressure is generally applied by screws which are plugged through bores in the flange leaves. Said flange leaves or flanges are generally welded to the pipe, this entailing complicated welding operations.
In the case of clamping connections, those end sections of the pipes or fluid line parts which are to be connected are completely surrounded by a clamping body. The clamping body is then drawn together by means of one or more screw connections and thereby wedges in those end sections of the pipes which are to be connected, wherein the region to be clamped together comprises virtually 360° and the surface pressure between the pipe and clamping body is built up uniformly. In this case, the permissible tightening torque of the screws has to be noted in order to obtain the required frictional connection between the clamping body and the pipes such that the tightness of the connection is ensured.
Furthermore, the prior art discloses sleeve connections for the interruption-free connection of pipes or fluid line parts. Sleeve connections of this type are used both for substantially unpressurized pipelines, such as, for example, channel pipes or cable protection pipes, and for pressurized pipelines, such as, for example, lines for gas, exhaust gas, drinking water or waste water. The sleeve connection has a sleeve element which can be produced, for example, by expanding an end section of a pipe. As an alternative, the sleeve element can be designed as a separate coupling sleeve and fitted on the end section of the pipe. Said sleeve connection is also referred to as a “plug-in sleeve connection” in which a free end section of a pipe is plugged into the sleeve element, wherein the free end section of the pipe is generally referred to as the pointed end. In order to seal the sleeve connection, a sealing ring which is inserted in a circumferential groove formed in the inner wall of the sleeve element is customarily provided.
A disadvantage of said sleeve connections is that they are generally not designed to be self-securing and are not designed to withstand tensile forces, and therefore there is the risk, should a tensile loading become effective, of the pipes or fluid line parts which are to be connected sliding apart and releasing the pipe connection or fluid line connection.
In order to prevent this, plug-in sleeve connections are known, in which, in order to secure the pipe connection, an annular clamping element is arranged in a special, encircling recess in front of the sealing ring, the clamping element being pressed against the pointed end under the action of the recess, which becomes narrower towards the sleeve entrance, and, by means of a frictional connection, prevents said pointed end from migrating out of the sleeve. In this case, the clamping ring can be specially roughened or toothed. It is disadvantageous, however, that visual checking of the securing means in the form of the clamping ring is not possible, since the clamping ring is arranged in the interior of the pipe connection between the pipes and checking is possible only if the pipe connection is released.
The use of a clamping element of this type furthermore has the disadvantage that the clamping element does not immediately come into effect but rather only after a certain starting distance, and therefore the tightness of the connection is not always ensured. Also, clamping elements of this type, which are generally of elastic design, withstand only a certain tensile force and are not suitable for relatively large tensile loadings. In particular in the case of pressure-loaded sleeve connections, there is therefore the risk of the sleeve connection becoming released under tensile loading. Furthermore, some countries have strict and prescribed requirements that the sleeve connection must withstand, for example, a tensile loading of several hundred Newtons and a predetermined torque acting on the connection.
There is therefore the need in fluid line connections of this type to provide a securing means which withstands high tensile forces, thus preventing the fluid line parts from sliding apart.